Hi Guys, thank you very much for your replies. Well this afternoon we chucked out some of the clapped out flats so I have no choice but to make some new ones. It seems that 3"x1" PAR is the preferred frame material but how do you join the pieces together? The old flats had various size frames with screws driven from the corners of the verticals into the ends of the horizontals. In principle I don't like having screws going parallel to the grain. I tried repairing/stiffening some of them using triangular metal pales from S***wF*x but found that they were too soft to be effective. Also what additional stiffening if any do people use? One horizontal piece across the centre or going the whole hog and fitting diagonal pieces between a centre horizontal and the top/bottom in the same way as a garden gate is often stiffened. I think that I'll use plywood to cover the frame. I hadn't realised that it was lighter than hardboard. We can't use calico as we have to store the flats stacked on top of each other under the stage and the risk of tearing it is fat too high. I liked the idea of hinges with removable pin to join the flats. I have a router hinge jig so this so it should be relatively easy to ensure alignment and a flush fit. Ynot, thanks for your offer but but I don't think it's right for us for us. Thanks again to you all for your help. Graham